Solid microspheres which are tacky and rubbery and prepared by suspension polymerization are disclosed in many prior patents, including U.S. Pat. No. 3,691,140 and the several patents referred to therein and U.S. Pat. No. 5,194,329 and the several patents referred to therein. The principal uses for those prior art microspheres are as low-tack adhesives for repositionable note pads. In that application the microspheres are disposed over a substrate such as paper in a thin layer characterized in that the individual microspheres are dispersed and spaced apart and not in contact with one another. This spacing apart of the microspheres is a factor enhancing their ability to be applied, removed and reapplied to surfaces without transfer of adhesive or damage to the surface and with the low-tack adhesion needed for easy removal.
In the arts of adhesive cushioning and mounting means it is well known to use layers or slabs of elastomeric material which possess qualities of tackiness and rubberiness. In footwear, for example, U.S. Pat. No. 4,970,807 teaches the deposit in a recess within a shoe sole of small balls of resilient polyurethane or rubber. The balls are pre-coated with an adhesive such as silicone rubber so that they form a body which can be handled as a self-contained unit during assembly. U.S. Pat. No. 5,024,880 also discloses a form of tacky elastomer suitable for shock dampening. Similarly, adhesive coated foams have been widely used as mounting "dots" which typically are separated from release sheets and then pressed into adherence with a surface such as a wall to provide tacky exposed faces for releasable attachment of various objects. The 3M Corporation of St. Paul, Minn., U.S.A. has marketed one form of these prior art elastomeric products under the designation "Mounting Squares".
In none of these prior art adhesive cushioning and mounting elastomers, however, has any known use been made of solid microspheres which are tacky and rubbery and prepared by suspension polymerization as in the previously mentioned microspheres for repositionable note papers. The conventional utilization of those microspheres in very thin layers with the individual microspheres dispersed measurably apart has made them well suited for low-tack repositionable note pads but not for cushioning or mounting means.
It is a principal object of the present invention to provide improved composite elastomeric articles for adhesive cushioning and mounting purposes which utilize a specifically modified form of known solid microspheres prepared by suspension polymerization.